1. Field of the Invention
This invention relates generally to air conditioning and heating systems and more specifically to methods and devices for cleaning heat exchanger fins and coils in the air ducts of such systems.
2. Description of the Prior Art
Many air conditioning and heating systems utilize air duct work for carrying fan-blown air to the desired locations in a building for heating or cooling the interior of the building. In order to heat or cool the air which is blown through the ducts, fin-type heat exchangers are transversely mounted in the air ducts. A heated or cooled heat transfer material such as a refrigerant is pumped through coils in the heat exchanger which heats or cools the fins attached to the coil. Generally, the fins are vertically oriented and the edges of the fins combine to form opposing walls of the heat exchanger. Thus, the air moving in the ducts must pass through the heat exchanger exchanging heat with the fins and coils as it so moves.
Although it is common to transversely mount air filters in the air ducts to prevent dust and other particles from being circulated with the air moving through the ducts, small particles of dust and other materials escape these filters and accumulate on the heat exchangers. Over a period of time, therefore, grease and dust accumulate on the fins and coils of the heat exchanger restricting the air flow through the heat exchanger and inhibiting heat transfer between the fins and the air. This reduces the efficiency of the heat exchange and increases the heating or cooling cost.
Recognizing this problem of accumulation of dust and grease on the fins and coils of heat exchangers, attempts have been made in the past to provide methods and devices for cleaning such heat exchangers. The most common method is to use a hand-pumped spray bottle containing a cleaning liquid. This bottle is hand-carried to the air duct location containing the heat exchanger and access panels in the air duct are removed. Often, access panels are not provided and it is necessary to cut an access panel in order to reach the heat exchanger. A spray wand from the bottle of cleaning liquid is then maneuvered through the access panel and the cleaning liquid is sprayed on the heat exchanger to remove the accumulations of dirt and grease.
U.S. Pat. No. 4,332,292 discloses a device for cleaning coils. In this device flexible hoses are disposed in an array within the air duct and pointed at the heat exchanger. A set of supply lines extends from each of the hoses in the array to a source of cleaning liquid which can automatically operate to supply liquid to the hoses. As liquid passes through the hoses they whip about to spray the liquid on different sections of the heat exchanger.
Neither of the above methods has been found to be satisfactory because either the man-hours involved in cleaning is too high or the expense of the automatic equipment, maintenance of the equipment and installation of the equipment is too high. Further, neither method cleans the heat exchanger as well as is desirable.